La(fe,si)13-based magnetic refrigeration material prepared from industrial-pure mischmetal as the raw material and preparation and use thereof

Abstract

The invention provides a La(Fe,Si) 13 -based magnetic refrigeration material prepared from industrial-pure mischmetal as the raw material, wherein the industrial-pure mischmetal is impurity-containing and naturally proportionated La—Ce—Pr—Nd mischmetal or LaCe alloy which, as the intermediate product during rare earth extraction, is extracted from light rare earth ore. The invention further provides the preparation method and use of the material, wherein the preparation method comprises the steps of smelting and annealing industrial-pure mischmetal as the raw material to prepare the La(Fe,Si) 13 -based magnetic refrigeration material. The presence of impurities in the industrial-pure mischmetal has no impact on the formation of the 1:13 phase, the presence of the first-order phase-transition property and metamagnetic behavior, and thus maintains the giant magnetocaloric effect of the magnetic refrigeration material. The preparation of La(Fe,Si) 13 -based magnetic refrigeration material from industrial-pure mischmetal reduces the dependency on high-purity elementary rare earth raw material; lowers the cost for manufacturing the material; and thus plays an important role in development of the magnetic refrigeration application of materials.

1 . A La(Fe,Si) 13 -based magnetic refrigeration material prepared from a raw material of an industrial-pure mischmetal, wherein the industrial-pure mischmetal is an impurity-containing and naturally proportionated La—Ce—Pr—Nd mischmetal or LaCe alloy which, as an intermediate product during rare earth extraction, is extracted from light rare earth ore, and the magnetic material has the NaZn 13 -type structure, wherein
 when the industrial-pure mischmetal is the impurity-containing La—Ce—Pr—Nd mischmetal extracted from light rare earth ore, the material is represented by the chemical formula: La 1-x (Ce,Pr,Nd) X (Fe 1-p-q Co p Mn q ) 13-y Si y A α , 
 wherein, A is one or more selected from elements C, H and B, 
 x is in the range of 0<x≦0.5, 
 p is in the range of 0≦p≦0.2, 
 q is in the range of 0≦q≦0.2, 
 y is in the range of 0.8<y≦1.8, 
 α is in the range of 0≦α≦3.0, 
 wherein, the relative molar ratio of the three elements Ce, Pr and Nd is the same as the natural proportion of Ce, Pr and Nd in the La—Ce—Pr—Nd mischmetal, and the total number of moles of Ce, Pr and Nd is x; in the La—Ce—Pr—Nd mischmetal, the molar ratio of the four elements La, Ce, Pr and Nd is the same as their natural proportion in the light rare earth ore; the La—Ce—Pr—Nd mischmetal has a purity of ≧95 wt. %; the La—Ce—Pr—Nd mischmetal contains impurities comprising one or more of Sm, Fe, Si, Mg, Zn, W, Mo, Cu, Ni, Ti, Th, Y, Ca, Pb, Cr, C, H and O; 
 when the industrial-pure mischmetal is the impurity-containing LaCe alloy extracted from light rare earth ore, the material is represented by the chemical formula: La 1-x-z Ce x R Z (Fe 1-p-q Co p Mn q ) 13-y Si y A α , 
 wherein, R is one or both selected from elements Pr and Nd, 
 A is one or more selected from elements C, H and B, 
 x is in the range of 0<x≦0.5, 
 z is in the range of 0≦z≦0.5, and x+z<1, 
 p is in the range of 0≦p≦0.2, 
 q is in the range of 0≦q≦0.2, 
 y is in the range of 0.8<y≦1.8, 
 α is in the range of 0≦α≦3.0, 
 wherein, the LaCe alloy has a purity of ≧95 at. %; and the atomic ratio of La:Ce in the alloy is the same as their natural proportion in the light rare earth ore; the LaCe alloy contains impurities comprising one or more of Pr, Nd, Sm, Fe, Si, Mg, Zn, W, Mo, Cu, Ni, Ti, Th, Y, Ca, Pb, Cr, C, H and O. 
 
     
     
         2 . The magnetic refrigeration material according to  claim 1 , wherein, where the industrial-pure mischmetal is the impurity-containing La—Ce—Pr—Nd mischmetal, the magnetic refrigeration material further comprises one or more elements selected from Sm, Mg, Zn, W, Mo, Cu, Ti, Ca, Pb, Cr and O; and where A in the chemical formula does not include element C or H, the magnetic refrigeration material further comprises one or more elements selected from Sm, Mg, Zn, W, Mo, Cu, Ti, Ca, Pb, Cr, C, H and O. 
     
     
         3 . The magnetic refrigeration material according to  claim 1 , wherein, where the industrial-pure mischmetal is the impurity-containing LaCe alloy, the magnetic refrigeration material further comprises one or more elements selected from Pr, Nd, Cu, Ni, Zn, Th, Y, Mg, Ca and O; an where the magnetic material is LaCeFeSi, the magnetic material further comprises one or more elements selected from Pr, Nd, C, H, Cu, Ni, Zn, Th, Y, Mg, Ca and O. 
     
     
         4 . A method for preparing a magnetic refrigeration material according to  claim 1 , comprising the steps of:
 1) preparing raw material according to the chemical formula, where A includes element H, the raw material other than H is prepared according to the chemical formula, the raw material comprises industrial-pure mischmetal, i.e., an impurity-containing and naturally proportionated La—Ce—Pr—Nd mischmetal or LaCe alloy which, as an intermediate product during rare earth extraction, is extracted from light rare earth ore; wherein, where the industrial-pure mischmetal is the impurity-containing La—Ce—Pr—Nd mischmetal extracted from light rare earth ore, the material is represented by the chemical formula: La 1-x (Ce,Pr,Nd) X (Fe 1-p-q Co p Mn q ) 13-y Si y A α , and where the industrial-pure mischmetal is the impurity-containing LaCe alloy extracted from light rare earth ore, the material is represented by the chemical formula: La 1-x-z Ce x R Z (Fe 1-p-q Co p Mn q ) 13-y Si y A α ;   2) preparing alloy ingots by arc melting technology, wherein the raw material prepared in step 1) is placed in an arc furnace, vacuumed, purged with argon gas, and smelted under the protection of argon gas so as to obtain the alloy ingots;   3) vacuum annealing the alloy ingots obtained in step 2) and then quenching the alloy ingots in liquid nitrogen or water so as to obtain the magnetocaloric material La 1-x-z Ce x R Z (Fe 1-p-q Co p Mn q ) 13-y Si y A α  or La 1-x (Ce,Pr,Nd) X (Fe 1-p-q Co p Mn q ) 13-y Si y A α  having a NaZn 13 -type structure;   wherein, where A in the above chemical formula includes element H, the method further comprises the step of 4) pulverizing the material obtained from step 3) and then annealing the resultant powder in hydrogen gas.   
     
     
         5 . The method according to  claim 4 , wherein, in the raw material La—Ce—Pr—Nd mischmetal, the molar ratio of the four elements La, Ce, Pr and Nd is the same as their natural proportion in the light rare earth ore; the La—Ce—Pr—Nd mischmetal has a purity of ≧95 wt. %, the La—Ce—Pr—Nd mischmetal contains impurities comprising one or more of Sm, Fe, Si, Mg, Zn, W, Mo, Cu, Ni, Ti, Th, Y, Ca, Pb, Cr, C, H and O. 
     
     
         6 . The method according to  claim 4 , wherein, the raw material LaCe alloy has a purity of ≧95 at. %; and the atomic ratio of La:Ce in the alloy is the same as their natural proportion in the light rare earth ore; the LaCe alloy contains impurities comprising one or more of Pr, Nd, Sm, Fe, Si, Mg, Zn, W, Mo, Cu, Ni, Ti, Th, Y, Ca, Pb, Cr, C, H and O. 
     
     
         7 . The method according to  claim 4 , wherein, in the raw material, where A includes element C, the element C is provided by FeC alloy; or where A includes element B, the element B is provided by FeB alloy. 
     
     
         8 . The method according to  claim 4 , wherein, the step 2) comprises the steps of placing the raw material prepared in step 1) into an arc furnace; vacuuming the arc furnace to reach a vacuum degree of less than 1×10 −2  Pa; purging the furnace chamber once or twice with an argon gas having a purity of higher than 99 wt. %; then filling the furnace chamber with the argon gas to reach 0.5-1.5 atms; and arcing so as to obtain the alloy ingots; wherein each alloy ingot is smelted at 1500-2500° C. for 1-6 times repeatedly. 
     
     
         9 . The method according to  claim 4 , wherein, the step 3) comprises the steps of annealing the smelted alloy ingots obtained from step 2) at 1000-1400° C. and under a vacuum degree of less than 1×10 −3  Pa for from 1 hour to 60 days; then quenching the alloy ingots in liquid nitrogen or water so as to prepare the magnetic refrigeration material La 1-x-z Ce x R Z (Fe 1-p-q Co p Mn q ) 13-y Si y A α  or La 1-x (Ce,Pr,Nd) X (Fe 1-p-q Co p Mn q ) 13-y Si y A α  with a main phase being of NaZn 13 -type structure. 
     
     
         10 . The method according to  claim 4 , wherein, the step 4) comprises the steps of pulverizing the material prepared in step 3) into an irregular powder with a particle size of less than 2 mm; placing the powder in a hydrogen gas with a purity of higher than 99 wt. % and at a pressure of 0-100 atms; and annealing the resultant at 0-600° C. for from 1 minute to 10 days. 
     
     
         11 . A magnetic refrigerator, comprising a magnetic refrigeration material according to  claim 1 . 
     
     
         12 . Use of a magnetic refrigeration material according to  claim 1 . 
     
     
         13 . The magnetic refrigeration material according to  claim 1 , wherein x is in the range of 0<x≦0.3. 
     
     
         14 . The magnetic refrigeration material according to  claim 1 , wherein the La—Ce—Pr—Nd mischmetal has a purity of ≧98 wt. %. 
     
     
         15 . The magnetic refrigeration material according to  claim 1 , wherein the atomic ratio of La:Ce in the alloy is 1:1.6-1:2.3. 
     
     
         16 . The method according to  claim 5 , wherein the La—Ce—Pr—Nd mischmetal has a purity of ≧98 wt. %. 
     
     
         17 . The method according to  claim 4 , wherein the La—Ce—Pr—Nd mischmetal has a purity of ≧98 wt. %. 
     
     
         18 . The method according to  claim 4 , wherein the atomic ratio of La:Ce in the alloy is 1:1.6-1:2.3. 
     
     
         19 . The method according to  claim 8 , wherein the smelting temperature is 1800-2500° C. 
     
     
         20 . The method according to  claim 10 , wherein the hydrogen gas is at a pressure of 10 −4 -100 atms; and the annealing is at 100-350° C. for from 1 minute to 3 days.